1. Field of the Invention
The present invention relates to a non-contact electric power supply system for movable sections for a rail-guided vehicle. More specifically, the present invention relates to the configuration of a non-contact electric power supply system for the stable supply of electric power to a lateral table and a turntable for a rail-guided vehicle.
2. Description of the Related Art
An electric feed cable secured to a rail on a main line, which itself ordinarily is fixed in place, and an electric feed line provided at a branch point, a rotating body, and similar movable bodies in a conventional non-contact electric power supply system are connected to form one loop among all electric feed lines by means of a connecting line connecting the main line and the movable bodies.
The overall configuration of a non-contact electric power supply system for a rail-guided vehicle, as embodied in the related art, is hereunder explained, utilizing FIG. 1.
A commercial power supply 1 consists of a power source received from, illustratively, a power company, through a power line in 50/60 Hz, 200/100V, and 3-phase units.
A first high-frequency power supply apparatus 2 is a high-frequency power supply apparatus in which a frequency is set by an inverter or like device to 10 kHz, for example, and which is capable of supplying a fixed current in the order of 100 A.
A first fixed rail 3 regulates the direction of the vehicle's movement so that the movement does not deviate from the rail. The first fixed rail 3 also supports the weight of the vehicle and holds electric feed cables, which are hereinafter described.
Electric feed cables 4 and 5 are connected to the first high-frequency power supply apparatus 2. Fixed on the first fixed rail 3, the feeder cables 4 and 5 consist of litz lines or like power lines for supplying electric power to the vehicle without contact therewith. A litz line, as contemplated by the present invention, consists of approximately 100 enamel-coated wires twisted together and further insulated. The cross-sectional diameter of a whole line is about 15-20 mm, and the current capacity thereof is on the order of 100 A.
Transition lines 6 and 7 are litz lines or like power lines, possessed of some degree of slackness, that connect the feeder cables 4 and 5 on the first fixed rail 3 with the feeder cables on a lateral table 8 (described hereinafter) to permit movement of the lateral table.
The lateral table 8 changes tracks for the vehicle and can change the course thereof, or conduct the vehicle to a feeder line. To change rails, the vehicle is brought to a stop at a prescribed position, at which the vehicle rests completely on a first and a second movable rail 9 and 10 (described hereinafter) of the lateral table 8. A track change is accomplished as the lateral table 8 is displaced parallel to the second movable rails 9 and 10.
The first movable rail 9 and the second movable rail 10 are used to change tracks for the vehicle on the lateral table 8 and move in concert with the parallel displacement of lateral table 8. Electric feed cables 11 and 12, and 14 and 15, are connected to transition lines 6 and 7 and comprise litz lines or like power lines fixed respectively on the first movable rail 9 and the second movable rail 10.
A connecting line 13 is a cable connecting respectively electric feed cables 11 and 14, and 12 and 15, and consists of a litz line or like power line fixed in place on the lateral table 8.
Transition lines 16, 17 are litz lines or like power lines, possessed of some degree of slackness, that connect electric feed cables 14 and 15 on the lateral table 8 with electric feed cables 19 and.20 on a fixed rail 18 (described hereinafter), to permit displacement of the lateral table 8.
The second fixed rail 18 is, illustratively, a rail in a fixed track comprising a main line for the vehicle. The function of the second fixed rail 18 is, like that of the first fixed rail 3, to regulate the direction of the vehicle's movement so that the movement does not deviate from the rails. Additionally, the second fixed rail 18 supports the weight of the vehicle and holds electric feed cables (described hereinafter).
Electric feed cables 19 and 20 are connected to transition lines 16 and 17 and consist of litz lines or like power lines, fixed on the second fixed rail 18 and supplying electric power to the vehicle without contact therewith.
Short circuit line 21 is a litz line or like power line for short-circuiting the electric feed cables 19 and 20 at the ends thereof.
In the above-described non-contact power supply system, a rail-guided vehicle travels above the power feed lines and performs tasks while being supplied with power. When operating the vehicle under normal conditions, the lateral table 8 is displaced parallel to the fixed rail 3 and the second fixed rail 18 and is adjusted positionally so that the movable rail 9 is disposed in the same plane as the first fixed rail 3 and the second fixed rail 18. The vehicle travels sequentially from fixed rail 3 to movable rail 9, and from movable rail 9 to fixed rail 18. To change tracks for the vehicle, the lateral table 8 undergoes parallel displacement until the second movable rail 10 assumes the same position as the first movable rail 9. A vehicle that has traveled on first fixed rail 3 or second fixed rail 18, while being supplied with power from electric feed cables 4 and 5, or 19 and 20, is brought to rest at a prescribed position on the second movable rail 10 of the lateral table 8, at which position all wheels of the vehicle are on the second movable rail 10.
Then, the lateral table 8 undergoes further parallel displacement until the second movable rail 10 returns to its original position. In the case of a feeder line for, illustratively, a secondary line, the vehicles commences movement on the feeder line at the terminus of the vehicle's parallel displacement. If, however, the lateral table 8 coincides with, illustratively, a maintenance station, a vehicle that has been displaced to that location undergoes maintenance or assumes a standby posture.
To facilitate rail movement, however, it is necessary to provide the transition lines joining electric feed cables with some degree of slackness. Where rails are affixed to a ceiling, the slack regions of the transition lines inevitably hang down, thus interfering with work and rail traffic below. This effectively dilutes the purpose of fixing the rails to a ceiling and undermines the utilization efficiency at locations where rails are so fixed, as well as the efficiency of work crews performing tasks beneath those locations.
Further, because the respective distances between outbound and inbound electric feed cables and between hanging outbound and inbound lines fluctuate in regions where the transition lines are slack, the overall inductance of the electric feed cables varies significantly. A high-frequency supply source is unable to follow the pace of the inductance change in the electric feed cables, even where a source-side feedback control endeavors to compensate for the change in output. Consequently, power output fluctuates, and an unstable power supply is likely, particularly in the case of output reduction.
Because the diameter of an electric feed cable is a relatively large 15-20 mm, the cable cannot be bent sharply, but rather must be deflected gradually. It is thus necessary to provide the electric feed cables with a hanging distance greater than the minimum movement distance required by a movable body. Even where rails are fixed on a floor, the transition lines must enjoy some degree of slackness. The transition lines in this case require a wider range of motion than that required in a ceiling installation. In consequence thereof, the circumvention of the electric feed cables becomes difficult. If the floor is of metal construction, moreover, the likelihood of a further increase in inductance and attendant output reduction increases, given the resultant conductive heating and excessive current.
Further, if rails are installed in a clean room, installation of the rails and electric feed cables must be undertaken with an eye toward reducing to the greatest extent possible the number of movable bodies, in order to minimize the generation of particles. When installing successively the electric feed cables corresponding to the movable rails for, illustratively, the fixed rails and the lateral table, the transition lines must be slack, and the movement thereof harmonized with that of the movable rails.